1. Field of the Invention
The present invention relates clock generators and, more particularly, to a clock generation system for generating a first clock signal at a first clock frequency and a second clock signal at a second clock frequency with a predetermined ratio to said first clock frequency, where the system comprises a clock signal generator providing the first clock signal, a frequency divider device having at least one frequency divider for dividing the first clock frequency by a first integer to produce a first auxiliary signal and for dividing the second clock signal by a second integer to produce a second auxiliary signal, a phase/period comparator configured to generate an error signal by comparing the first and second auxiliary signals, and a voltage-controlled oscillator controlled in dependence on the error signal to generate the second clock signal.
2. Description of the Related Art
EP 2 207 263 A1 discloses two clock generator systems for generating second clock signals with slightly different frequency ratios to the first clock signal so that the second clock signals have slightly different frequencies. Given suitable selection of integer divisors of the clock system, a single such system may be used to generate the second clock signal with the desired slightly different frequency to the first clock signal.
In such a conventional system, the first and second clock signals are processed by different circuit sections before reaching the phase/period comparator. Therefore, any mismatch between the different circuit sections, such as different propagation delay times or offset voltages due to manufacturing tolerances, thermal drift or aging, may result in an error of the wanted frequency ratio between the first and second clock signals.